Welcome aboard, Kelly!
You must be asking about the Key To The World Card which every guest receives onboard. These Key To The World Cards serve as your stateroom key, identification, charge card and more! I usually carry my kids' keys, and you may consider doing the same, depending on how old your granddaughter is. Honestly, if she is under 11, and not heading out and about the ship on her own, she won't need to hang onto it for herself, as long as you have it when you're with her as you disembark the ship and re-board in the ports of call.
When little ones check into the
Oceaneer Club and Lab, the parents' cards are scanned, not the kids', so the kiddos don't have to keep track of their cards in the clubs. Kids receive a Youth Activities Wristband to wear that they use to scan when parents take them in and out of the clubs, so your granddaughter can wear that while you hold onto her key card.
But, for keeping the key cards handy, lanyards that have a plastic pocket attached work perfectly, and it's a lot of fun to sport a fun Disney-themed lanyard onboard. Check out the options you can order ahead of time at Disneystore.com, but there are way more designs to choose from in the
Gift Shops onboard. My kids do love to wear their lanyards with trading pins because there is quite a bit of pin trading onboard. Cast Members outside Cabanas have trading pins on their lanyards, as do the Cast Members in the Gift Shops. The last night onboard there is a fun event called Officer Pin Trading, when guests can trade Disney pins with the ship's officers. Your granddaughter may have a lot of fun participating throughout the cruise!
I hope those details help as you get ready to set sail, Kelly! Have a magical cruise!
Marcy